Reels for supporting wound flexible media are employed to both store and facilitate the dispensing of wound media such as rope, wire, chain, and strings of parts. The essential elements of a reel include its core, around which the flexible medium is wound, and its flanges, which prevent the wound flexible medium from migrating axially off of the core. Reels intended for industrial use can vary greatly in size.
Well-designed reels must combine a high strength-to-weight ratio with low manufacturing cost. One reel design that has gained popularity is a reel in which the core is constructed of either a pressed paperboard material or extruded plastic, and in which the flanges are constructed of a composite or plastic material. The use of paper and plastic components, in general, provides a high strength-to-weight ratio and facilitates the use of relatively straightforward and relatively inexpensive manufacturing techniques. Another lightweight reel design consists of a pressed paperboard core and corrugated paper flanges. While such all-paper reels provide significant economy and light weight, all-paper reels are generally not suitable for certain medium to heavy duty applications because the paper flanges do not have the strength of plastic, wood, or steel flanges. Accordingly, for medium to heavy duty reel applications, plastic or composite flanges provide an advantageous combination of manufacturability, light weight, and strength.
Reels having composite or plastic flanges are relatively simple to manufacture. The flanges may be formed using known injection molding techniques. The flanges are then attached to the core to form a reel.
During use, reels are subject to many extraneous forces which can possibly damage the reels. For instance, a user may grip the reel by one of its flanges and lift the reel off of the floor. If the reel is not carrying any wound media, the reel is less susceptible to damage from such lifting. On the other hand, if the reel is loaded with a heavy metal wound medium, then the weight of the loaded reel can cause the gripped flange to bend and/or warp when the reel is lifted by the flange. In order to avoid damage caused by such lifting, the typical flange is designed with wall thicknesses that are sufficient to provide the necessary strength and structural integrity. Of course, with increased wall thicknesses also comes increased material costs and weight, neither of which is desirable.
Another way in which a reel may be damaged is if an extraneous force is exerted on a flange, such as if the reel is dropped. Such a force exerted on a flange will usually damage the pressed cardboard core. Particularly subject to damage are the ends of the core that engage the flanges. It has been found that an end of a core tends to tear or buckle inwardly when a sufficient force is exerted on the corresponding flange.
What is needed, therefore, is a reel that is less subject to damage from extraneous forces and yet does not require an increased amount of material.